Patterson function from low-energy electron diffraction measured intensities and structural discrimination

Surface patterson functions have been derived by direct inversion of experimental low-energy electron diffraction I-V spectra measured at multiple incident angles. The direct inversion is computationally simple and can be used to discriminate between different structural models. (1x1) YSi2 epitaxial layers grown on Si(111) have been used to illustrate the analysis. We introduce a suitable R factor for the Patterson function to make the structural discrimination as objective as possible. From six competing models needed to complete the geometrical search, four could easily be discarded, achieving a very significant and useful reduction in the parameter space to be explored by standard dynamical low-energy electron diffraction methods. The amount and quality of data needed for this analysis is discussed